#!/user/bin/python
# -*- coding: UTF-8 -*-

# 题目：画椭圆。　
#
# 程序分析：使用 Tkinter。

if __name__ == '__main__':
    from Tkinter import *
    x = 360
    y = 160
    top = y - 30
    bottom = y - 30
    canvas = Canvas(width = 400, height = 600, bg = 'white')
    # canvas.create_oval(300, 200, 0, 300)
    for i in range(20):
        # x1,y1,x2,y2
        canvas.create_oval(250 - top, 250 - bottom, 250 + top, 250 + bottom)
        top -= 5
        bottom += 5
    canvas.pack()
    mainloop()